Combine the functionality of test_support.run_unittest()
and test_support.run_classtests() into run_unittest()
and use it wherever possible.

Also don't use "from test.test_support import ...", but
"from test import test_support" in a few spots.

From SF patch #662807.
diff --git a/Lib/test/test_cfgparser.py b/Lib/test/test_cfgparser.py
index bc0ef5e..b1b495e 100644
--- a/Lib/test/test_cfgparser.py
+++ b/Lib/test/test_cfgparser.py
@@ -322,11 +322,11 @@
 
 
 def test_main():
-    suite = unittest.TestSuite()
-    suite.addTests([unittest.makeSuite(ConfigParserTestCase),
-                    unittest.makeSuite(RawConfigParserTestCase),
-                    unittest.makeSuite(SafeConfigParserTestCase)])
-    test_support.run_suite(suite)
+    test_support.run_unittest(
+        ConfigParserTestCase,
+        RawConfigParserTestCase,
+        SafeConfigParserTestCase
+    )
 
 if __name__ == "__main__":
     test_main()